1. Field of the Invention
This invention relates generally to indexing devices for use on conveyors and more particularly to a new and useful all purpose indexing device for use in interrupting the motion of baking trays on continually moving conveyors.
2. Description of the Prior Art
Baking tray indexing devices have been known which interrupt the motion of a baking tray on a continuously moving conveyor that utilize a plurality of indexing fingers movably suspended over the conveyor and engagable with indentations in the baking trays. In the past, the motion of these indexing fingers has been realized by the use of parallel bars and linkages connected between the stationary conveyor frame and the movable indexing fingers. Disadvantages of this arrangement include breakage of the indexing fingers due to the rigidity of the structure in the direction of motion of the conveyors and a lack of adjustment in the vertical travel of the indexing fingers from an upper clear position, allowing the trays to travel undisturbed under the arrangement to a lower engaging position, to interrupt the motion of the baking trays.
Another disadvantage of this arrangement was the tendency of the linkages to jam in an "up" position which required the assistance of a mechanic to unjam the linkages and restart the dough-feeding process.
In addition, the arrangement afforded no vertical fine adjustment of the indexing fingers in the linkage frame. Problems of operation in the prior system arose after a successful indexing of a single pan. The uniform spacing of the indentations in one pan not being equal to the spacing between the last row of indentations of a pan to the first row of indentations of the succeeding pany on the conveyor led to the back-up and jamming of baking pans on the conveyor. Also, since the reciprocal vertical motion of the indexing fingers was timed to coincide with the spacing of the indentations, the possibility arose that the indexing fingers would be brought down upon a leading or trailing edge of a baking pan due to the non-uniformity of spacing at these locations. The motion of the conveyor in the prior art systems was continuous and no sensing means was incorporated in these systems to sense the beginning or end of a baking pan and thus avoid the above problem.
Other limitations of the prior art systems were that due to the nature of the indexing, baking pans having small and closely spaced indentations could not successfully be used therein. Also, the range of sizes and shapes of spacing and indentations in baking pans was severely limited by the lack of adjustment in the speed of the conveyor.